Rewrite ${((3^{-10})(7^{-5}))^{-4}}$ in the form ${3^n \times 7^m}$.
Explanation: ${ ((3^{-10})(7^{-5}))^{-4} = (3^{(-10)(-4)})(7^{(-5)(-4)})} $ ${\hphantom{ ((3^{-10})(7^{-5}))^{-4}} = 3^{40} \times 7^{20}} $